Solid composite backing structure for single welding

ABSTRACT

A backing material, for use in butt or fillet welding, adapted to be placed and retained under or behind a joint to improve the quality of the weld at the root, the structure being composed of layers of different granular fluxes solidified into a rigid formation.

United States Patent Arikawa et a1. 1451 Sept. 5, 1972 54 SOLD)COMPOSITE BACKING 3,360,350 12/1967 sama ..29/197 STRUCTURE FOR SINGLEWELDING 3,432,915 3/ 1969 Doyle ..228/50 EW? m W- 3132233 llii fiiSfifiiifi'ffiiiiiiiiii:11131331553528 53 swam, Kamakura'sh" 2,558,4116/1951 Austin et a1. ..228/50 2,820,427 1/1958 Chyle et al ..228/50 731Assignee: Kobe S1661 1,111., Kobe-shi, Japan 2,916,001 12/1959 Chyle eta1 ..228/50 2,616,384 11/1952 McBride ..113/110 [221 Flled 19673,365,566 1/1968 Kuder ..228/50 21 App], No 33,122 1,650,905 Ill 1927Mills ..113/116 Primary ExaminerJohn F. Campbell [30] Foreign ApphcammPnonty Data Assistant Examiner-R. J. Craig May 9, 1966 Japan ..41/29503Y Lind & Pollack 52 US. Cl. ..228/50, 29/182.2, 29/491, [57] ABSTRACT 18/23 A backing material, for use in butt or fillet welding, [51] Int.Cl. ..B23k 5/22 adapted to be placed and retained under or behind aField of 8/5 joint to improve the quality of the weld at the root, the

148/23, 26; 219/146; 75/94 structure being composed of layers ofdifferent granular fluxes solidified into a rigid formation. 56 R 1 tedeerencesCl UNITED STATES PATENTS 3,309,196 3/1967 Kaneko et a1 ..148/26P'A'IENIEDsEP 1912 v 3,688,967

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sum 2 or 2 mnsnYnsu Hell/A0941 mu HITOS Si /hm, INVEATORS IF AJLMZZ $14SOLID COMPOSITE BACKING STRUCTURE FOR SINGLE WELDING CROSS REFERENCE TORELATED APPLICATIONS Reference is made to Japanese patent applicationNo. 41/29,503, filed May 9, 1966.

BACKGROUND OF THE INVENTION This invention relates to welding and inparticular to solid composite backing structures for use in weld jointswelded from a single side.

Hitherto, it has been extremely difficult to perform such single sidewelding on certain structures such as butt or fillet weld structures.

An object of the present invention is therefore to provide a solidcomposite backing structure for enabling such difficult welds tobe madewith ease and at a low cost.

As a means for backing a joint to be welded from one side only, it hasbeen conventional to use a copper backing strip. However, such use hadcertain disadvantages and, consequently, a process was developed forovercoming such disadvantages by utilizing flux powder. However, the useof a loose powdered flux as a backing material is very inconvenientbecause it is difficult to handle and to spread uniformly in desiredthickness so as to satisfactorily support the molten metal, andtherefore this process is of little practical value.

SUMMARY OF THE INVENTION The present invention provides a reliable andpracticable backing structure which eliminates the defects in the use offlux powder while making the best use of the advantages of copperbacking strips. The invention primarily resides in solidifying thewelding flux to a rigid formation by which the weld metal can besupported lining the solidified welding flux layer with a second layerof similarly solidified refractory material so as to endow the backingstructure with a fireproof property and thereby enhance the slagproducing faculty of the welding flux.

Thus, the present invention provides a solid composite backing structurefor use on single side welded joints which comprises a of welding fluxlayer and a refractory flux layer, said welding flux layer being in theform of a solid body backed with a said refractory flux layer which isalso in the form of a solid body, the free surface of said welding fluxlayer being the backing surface of said structure. The present inventionalso provides a solid composite backing structure for single sidewelding which comprises a welding flux layer, a refractory flux layerand a metallic support therefor, said refractory flux layer being in theform of a solid body which is retained by said metallic support, andsaid welding flux layer being similarly solidified and lined with therefractory flux layer, one face of said welding flux layer serving as abacking surface.

The terms welding flux layer" and refractory flux layer as employed inthe application refer, respectively, to a solid body prepared eitherfrom compound flux powders usually employed as welding flux to form amaterial which melts at the welding temperature of the metals to bejoined together and to a solid body prepared from the addition of arefractory component to a conventional welding flux component or a solidmass of refractory material which does not melt at the weldingtemperature of the metals to be joined together.

For example, the materials mixed for composing the welding flux layeraccording to this invention are inorganic compounds, such as SiO A1 0CaO, MgO, ZrO TiO MnO BaO, CaCO BaCO MgCO CaF, etc., while the materialsassorted for composing the refractory flux layer consist mainly ofrefractory materials, such as MgO, A1 0 SiO and the like. Thesematerials are formed into desired shapes by addition of water glass,bentonite, or other suitable binders, and are then solidified.

Further objects and advantages of this invention will further becomeapparent from the following detailed description and from theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of oneembodiment of the weld backing structure in accordance with the presentinvention;

FIG. 2 is a sectional view of the backing strip of FIG. 1 as applied toa single-V grooveweld;

FIGS. 3 and 4 are sectional views of further embodiments of thisinvention;

FIGS. 5 and 6 are perspective views of still further embodiments of thisinvention;

FIGS. 7 and 8 are sectional views of the embodiments of FIGS. 5 and '6as applied to two different types of welds; and I 1 FIG. 9 is aplurality of sectional views illustrating further embodiments of thisinvention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring to FIG. 1, anembodiment of the invention is shown having a solid refractory fluxlayer 2 and a solid welding flux layer 3, said layers being ofappropriate thickness and placed one upon the other so as to form aunitary construction. In FIG. 2, the backing structure of FIG. 1 isshown as applied to the root opening of metal members 4 to be welded,with the upper face of the welding flux layer 3 placed behind saidopening and in contact with the under faces of the members 4. Thisbacking structure can be secured to the metal members in a suitablemanner, for example, by tacking welds 5 (FIG. 7) or by securing withribs. It may be supported by separate sheet metals and then secured by asuitable jig fixture. Alternatively, it may be secured by employing anadhesive tape which is made to stick on the back face of the parentmetal members.

With the above arrangement, the welding operation may be performed fromthe upper side of the joint (see FIGS. 7 and 8.). In the weldingoperation, the tendency of the molten metal 6 to flow down to the backside of the joint will produce pressure on that portion of welding fluxlayer 3 which has been molten and converted to slag by the welding heat,and consequently, this supporting action serves to produce a betterappearing and smother back weld or reverse bead formation.

In the use of the backing structures of this invention in a weldingoperation, it will be apparent that, even when for welding arc digsextremely deeply into the root of the joint, the molten metalnevertheless may be well supported by the refractory flux layer 2disposed underneath the welding flux layer 3, and thus any seriousdamage can be entirely avoided.

By suitably selecting or controlling the thickness of the welding fluxlayer 3, the depth of the slag produced during the welding operation canbe controlled and thus the height of excess metal of a reverse bead canbe regulated easily as desired.

In addition to the above, this invention has a further advantage inthat, even if the welding arc is so varied during the operation as toseriously change the melting action, or if the welding is performedunder such severe conditions that surplus molten metal is producedrapidly, the uniformity of the reverse bea is, nevertheless, maintained.

FIGS. 3 and 4 show modifications of the compound backing structure shownin FIG. 1.

FIGS. 5 and 7 illustrate another modification of the present invention,wherein a metal supporting member is added for the purpose ofreinforcement. As shown in FIG. 5, metal casing 1 of channel shaped ironis filled with refractory flux layer 2 at the bottom and on said layer 2is superposed welding flux layer 3. Preferably the surface of layer 3 isflush with the top edge of metal casing l. The top face of welding fluxlayer 3 is exposed at the opening of casing 1, while refractory fluxlayer 2 is embedded within the casing. FIG. 7 shows an application ofthis type of backing strip to a butt joint weld wherein two metalmembers 4 are to be welded together.

Solid backing structures according to this invention can similarly beemployed in fillet welds for such types of joints as T, V or the like.FIG. 6 exemplifies one form of a solid backing structure particularlyadapted for use in fillet welds. As shown in FIG. 6, refractory fluxlayer 2 is secured rigidly in metal casing l, and on top of said layer 2is fixedly mounted welding flux layer 3 which takes the form of atriangular prism. This backing structure can also be utilized withoutaddition of metal casing 1. FIG. 8 shows an application of this type ofbacking structure to a fillet weld. The bevelled faces of the backingstructure shown in FIG. 6 are brought firmly into contact with thecorresponding back faces of the metal members 4, as is clear from FIG.8, and retained in this position by any suitable means (not shown). Theweld is now made from one side of the joint. The, welding flux layer 3becomes partially slagged by the action of the welding heat and thusserves to control the shape of the reverse bead.

It will be apparent that the above backing structure can be used withflexibility for other joints joint modified, in any other corner joint,such as for example a surf joint, i.e. wherein two plates of widelydifferent thicknesses are to be joined together, or corrugated bulkheadswherein the plates to be welded are positioned at various angles witheach other.

FIG. 9 is a series of illustrations, a to i, showing furthermodifications of the backing structure of the present invention. Asshown in a, a part at the bottom of the refractory flux layer 2 has beenreplaced with a different refractory material 2' which is cheaper andmore hygroscopic. Alternatively, this part 2 may be entirely eliminatedso as to form a cavity therein and the bottom side of layer 2 isretained by a supporting plate. In b, metal casing l is provided withinwardly projecting spikes 7 for retaining refractory layer 3 in placeso that it is particularly adapted to resist vibrations and impact. In0, metal casing 1 is formed in the sectional shape of an arcuate cup andthe refractory flux layer 2 has incorporated therein a suitable amountof metallic powder 8 for improving its thermal and physical properties.In d, a sheet of film 9, such as cellophane or the like, is attached tothe top surface of welding flux layer ,3 to render the stripanti-hyposcopic and at the same time to make it easy to handle as wellas to minimize accidental breakage. In e, two exposed faces ofrefractory flux layer 2 make a right angle with each other and aprismatic portion thereof is replaced with welding flux layer 3 havingdissimilar sides exposed so that it may be convenient for use in filletwelds having different leg lengths In f, a modification of the structureshown in FIG. 6 is illustrated. Two side walls of metal casing 1 aredirectly coupled to the ends of a V-shaped section of welding flux layer3 so that refractory flux layer 2 is completely covered thereby. The topangle of said layer 3 may either be obtuse or even arcuate instead ofrectangular. In g, a suitable fitting means 10 isprovided on metalcasing 2 for easy handling of the structure. In 11, metal bar 1 isprovided with holes I 1 extending therethrough either for connecting twoor more structures together or for facilitating conveyance or attachmentby use of wire, etc. In 1', there is shown a backing structureparticularly adapted for use in the field where the workpieces tobewelded vary widely in size and shape. As a metal support, a piece ofsheet steel 1 is utilized, the surface of which is coated withrefractory compounds in the, form of a solution, which is then dried toform a solid refractory flux layer 2. Afterwards, welding flux layer 3is stuck on top of layer 2 firmly to construct a unitary formation.The'structure produced as above may be used by simply forming it to anydesired shape according to the needs of the workpieces to be welded inthe field.

While the invention has been described in it presently preferred forms,it is to be realized that many changes to the instant embodiments may bemade without departing from the scope and concept of the invention.

The following is claimed:

1. A solid composite backing structure for use in the welding of jointseffected from a single side comprising a welding flux layer having theproperty of being meltable and convertible to slag by welding heat and arefractory flux layer being capable of supporting thereon molten metaldue to welding heat without being melted by welding heat wherein saidwelding flux layer is in the form of a single solid body formed fromcompound flux powders which are solidified by the inclusion therein ofbinders and said refractory flux layer is similarly in the form of asingle solid body formed from refractory flux powders which aresolidified by the inclusion of binders and further provided that saidwelding flux layer is attached to and supported by said refractory fluxlayer such that the free surface of the welding flux layer constitutesthe backing surface of the composite structure.

2. A solid composite backing structure as claimed in claim I whereinsaid binders included in the welding flux layer are taken from the groupconsisting of water glass and bentonite and wherein said bindersincluded in the refractory flux layer are taken from the groupconsisting of water glass and bentonite.

3. A solid composite backing structure as claimed in 5 claim 1 whereinsaid refractory flux layer is supported by a metallic support.-

2. A solid composite backing structure as claimed in claim 1 whereinsaid binders included in the welding flux layer are taken from the groupconsisting of water glass and bentonite and wherein said bindersincluded in the refractory flux layer are taken from the groupconsisting of water glass and bentonite.
 3. A solid composite backingstructure as claimed in claim 1 wherein said refractory flux layer issupported by a metallic support.